Swelling Properties Of Hydrogels Research Articles

Structure Effects on Swelling Properties of Hydrogels Based on Sodium Alginate and Acrylic Polymers.

Hydrogels based on sodium alginate (SA) and partially neutralised poly(acrylic acid) were obtained by radical polymerisation. The hydrogels were cross-linked with N,N'-methylenebisacrylamide (MBA), simultaneously grafting the resulting polymer onto SA. The findings of the FTIR spectroscopy showed that all of the hydrogels were effectively synthesized and sodium alginate was chemically bonded with the poly(sodium acrylate) matrix. DSC analysis of the melting heat and glass transition parameters indicated that the hydrogel structure had changed as a result of the cross-linking process. Sodium alginate and MBA were tested at different concentrations to determine how they affected the hydrogel properties. A very high content of the biopolymer, i.e., sodium alginate, was used in our research, up to 33 wt%. This resulted in durable and stable hydrogels with a very high ability to uptake water, comparable to hydrogels based on synthetic polymers only. The ability to swell is inversely proportional to the quantity of MBA present. By increasing the amount of sodium alginate in the hydrogel, the ability of the hydrogel to absorb water is reduced. However, water uptake remains relatively high at 350 g·g-1, even for the hydrogel with the highest SA content.

Developing biomass-modified hydrogel with high mechanical strength by a rosin-based crosslinking agent

Hydrogels are used in diverse applications owing to their superior water absorption and flexibility. At present, preparing hydrogels with high mechanical strength is becoming a hot topic. Hence, acrylpimaric acid-based acrylamide (APAAM) crosslinker were prepared from acrylpimaric acid, a derivative of natural rosin. The APAAM crosslinker synthesized a series of N, N-dimethylacrylamide/acrylamide (DMAA/AM) biomass-modified hydrogels with different crosslinking agent additions. The chemical structure, surface morphology, mechanical properties, rheological properties, and swelling properties of DMAA/AM hydrogels were investigated. The results showed that the tensile strength and compressive strength of hydrogels with APAAM (2.16 MPa, 874%) as a crosslinker are 15 times higher than the hydrogel with N, N′-methylene diacrylamide (BIS) (0.142 MPa, 254%) as crosslinker. This improvement benefit from the introduction of a rosin rigid ring. The swelling and thermal stability properties of hydrogels with APAAM as the crosslinker are also better than those of hydrogels prepared with BIS as the crosslinker. Besides, the mechanical strength and swelling properties of the hydrogels can be adjusted by the addition of an APAAM crosslinking agent. It was believed that this work provided a significant method for developing favorable mechanical properties for biomass-modified hydrogels.

Hydrogel Encapsulating Wormwood Essential Oil with Broad-spectrum Antibacterial and Immunomodulatory Properties for Infected Diabetic Wound Healing.

The integration of hydrogels with bio-friendly functional components through simple and efficient strategies to construct wound dressings with broad-spectrum antibacterial and immunomodulatory properties to promote the healing of infected diabetic wounds is highly desirable but remains a major challenge. Here, wormwood essential oil (WEO) is effectively encapsulated in the hydrogel via an O/W-Pickering emulsion during the polymerization of methacrylic anhydride gelatin (GelMA), acrylamide (AM), and acrylic acid N-hydroxysuccinimide ester (AAc-NHS) to form a multifunctional hydrogel dressing (HD-WEO). Compared with conventional emulsions, Pickering emulsions not only improve the encapsulation stability of the WEO, but also enhance the tensile and swelling properties of hydrogel. The synergistic interaction of WEO's diverse bioactive components provides a broad-spectrum antibacterial activity against S. aureus, E. coli, and MRSA. In addition, the HD-WEO can induce the polarization of macrophages from M1 to M2 phenotype. With these advantages, the broad-spectrum antibacterial and immunomodulatory HD-WEO effectively promotes the collagen deposition and neovascularization, thereby accelerating the healing of MRSA-infected diabetic wounds.

Fast Visible-Light 3D Printing of Conductive PEDOT:PSS Hydrogels.

Functional inks for light-based 3D printing are actively being searched for being able to exploit all the potentialities of additive manufacturing. Herein, a fast visible-light photopolymerization process is showed of conductive PEDOT:PSS hydrogels. For this purpose, a new Type II photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine (TEA), and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is investigated for the visible light photopolymerization of acrylic monomers. PEDOT:PSS has a dual role by accelerating the photoinitiation process and providing conductivity to the obtained hydrogels. Using this PIS, full monomer conversion is achieved in less than 2min using visible light. First, the PIS mechanism is studied, proposing that electron transfer between the triplet excited state of the dye (3 Rf*) and the amine (TEA) is catalyzed by PEDOT:PSS. Second, a series of poly(2-hydroxyethyl acrylate)/PEDOT:PSS hydrogels with different compositions are obtained by photopolymerization. The presence of PEDOT:PSS negatively influences the swelling properties of hydrogels, but significantly increases its mechanical modulus and electrical properties. The new PIS is also tested for 3D printing in a commercially available Digital Light Processing (DLP) 3D printer (405nm wavelength), obtaining high resolution and 500µm hole size conductive scaffolds.

Studies on PVP-Based Hydrogel Polymers as Dressing Materials with Prolonged Anticancer Drug Delivery Function.

Tamoxifen is a well-known active substance with anticancer activity. Currently, many investigations are performed on the development of carriers that provide its effective delivery. Particular attention is directed toward the formation of cyclodextrin-drug complexes to provide prolonged drug delivery. According to our knowledge, carriers in the form of polyvinylpyrrolidone (PVP)/gelatin-based hydrogels incorporated with β-cyclodextrin-tamoxifen complexes and additionally modified with nanogold have not been presented in the literature. In this work, two series of these materials have been synthesized-with tamoxifen and with its complex with β-cyclodextrin. The process of obtaining drug carrier systems consisted of several stages. Firstly, the nanogold suspension was obtained. Next, the hydrogels were prepared via photopolymerization. The size, dispersity and optical properties of nanogold as well as the swelling properties of hydrogels, their behavior in simulated physiological liquids and the impact of these liquids on their chemical structure were verified. The release profiles of tamoxifen from composites were also determined. The developed materials showed swelling capacity, stability in tested environments that did not affect their structure, and the ability to release drugs, while the release process was much more effective in acidic conditions than in alkaline ones. This is a benefit considering their use for anticancer drug delivery, due to the fact that near cancer cells, there is an acidic environment. In the case of the composites containing the drug-β-cyclodextrin complex, a prolonged release process was achieved compared to the drug release from materials with unbound tamoxifen. In terms of the properties and the composition, the developed materials show a great application potential as drug carriers, in particular as carriers of anticancer drugs such as tamoxifen.

Preparation of Hydrogels Based on Modified Pectins by Tuning Their Properties for Anti-Glioma Therapy

The extracellular matrix (ECM) of the central nervous system (CNS), characterized by low stiffness and predominance of carbohydrates on protein components, mediates limited cell proliferation and migration. Pectins are polysaccharides derived from plants and could be very promising for a tunable hydrogel design that mimics the neural ECM. Aiming to regulate gel structure and viscoelastic properties, we elaborated 10 variants of pectin-based hydrogels via tuning the concentration of the polymer and the number of free carboxyl groups expressed in the degree of esterification (DE). Viscoelastic properties of hydrogels varied in the range of 3 to 900 Pa for G' and were chosen as the first criteria for the selection of variants suitable for CNS remodeling. For extended reciprocal characterization, two pairs of hydrogels were taken to test pectins with opposite DEs close to 0% and 50%, respectively, but with a similar rheology exceeding 100 Pa (G'), which was achieved by adjusting the concentration of pectin. Hydrogel swelling properties and in vitro stability, together with structure characterization using SEM and FTIR spectroscopy, displayed some differences that may sense for biomedical application. Bioassays on C6 and U87MG glioblastoma cultures testified the potential prospects of the anti-glioma activity of hydrogels developed by decreasing cell proliferation and modulating migration but supporting the high viability of neural cells.

Research Advances in Mechanical Properties and Applications of Dual Network Hydrogels

Hydrogels with a three-dimensional network structure are particularly outstanding in water absorption and water retention because water exists stably in the interior, making the gel appear elastic and solid. Although traditional hydrogels have good water absorption and high water content, they have poor mechanical properties and are not strong enough to be applied in some scenarios today. The proposal of double-network hydrogels has dramatically improved the toughness and mechanical strength of hydrogels that can adapt to different environments. Based on ensuring the properties of hydrogels, they themselves will not be damaged by excessive pressure and tension. This review introduces preparation methods for double-network hydrogels and ways to improve the mechanical properties of three typical gels. In addition to improving the mechanical properties, the biocompatibility and swelling properties of hydrogels enable them to be applied in the fields of biomedicine, intelligent sensors, and ion adsorption.

A green approach to synthesize silver nanoparticles in gelatin/poly(2-hydroxyethylmethacrylate-co-2-acrylamido-2-methyl-1-propanesulfonic acid) hydrogels with Verbascum Longipedicellatum extract and their antibacterial activity

This study aimed to explain the production and the characterization of gelatin/poly(2-hydroxyethylmethacrylate-co-2-Acrylamido-2-methyl-1-propanesulfonic acid), Gel/p(HEMA-co-AMPS), hydrogels including silver nanoparticles (AgNP) that were developed with a simple, cost-effective and environmentally-friendly process. Silver ions were added to the Gel/p(HEMA-co-AMPS) hydrogel matrix synthesized via free radical polymerization, and silver nanoparticles were developed by in-situ reduction of silver ions (Ag+) in the swollen hydrogel using Verbascum Longipedicellatum plant extract. The structure and morphology of the prepared nanocomposite hydrogel were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy-energy-dispersive X-ray spectroscopy (TEM-EDX), X-ray diffraction analysis (XRD) and thermogravimetric analysis (TGA). In addition, the swelling properties of hydrogels were investigated and AgNPs embedded in the hydrogel network were found to absorb more water, improving the swelling properties of hydrogels. Finally, the antibacterial activity of silver nanocomposites against S. aureus, E. faecalis, B. Subtilis, B. cereus, E. coli, P. aeruginosa as bacterial agents and C. albicans as fungal agent was examined. Therefore, the present study offers a multi-component hydrogel containing AgNPs with low-cost and environmentally-friendly fabrication process for application as bactericidal materials in biotechnology and biomedical fields.

Super-Adsorptive Biodegradable Hydrogel from Simply Treated Sugarcane Bagasse.

There is a great demand for biodegradable hydrogel, and cellulose enriched wastes materials are widely used to serve this purpose for various advance applications (e.g., biomedical and environmental). Sugarcane bagasse is cellulose-enriched agro-waste, abundantly grown in Bangladesh. This study aimed to treat sugarcane bagasse-based agro-waste using a sustainable and ecofriendly approach to produce hydrogel with super-swelling capacity for adsorption of copper, chromium, iron ions, methylene blue and drimaren red dyes. To increase the swelling property of hydrogels, copolymerization of hydrophilic monomers is an effective technique. Therefore, this study aimed to prepare hydrogel via free radical graft-copolymerization reaction among acrylamide, methyl methacrylate and treated bagasse in the presence of N,N-methylene-bis-acrylamide as a crosslinker and potassium persulphate as an initiator. To obtain maximum yield, reaction conditions were optimized. It was found that hydrogel obtained from chemically treated sugarcane bagasse showed maximum water absorption capacity of 228.0 g/g, whereas untreated bagassebased hydrogel could absorb ~50 g/g of water. Maximum adsorption capacity of 247.0 mg/g was found for copper ion. In addition, organic pollutant removal from industrial effluent also showed good performance, removing >90% of methylene blue and 62% of drimaren red dye, with shorter kinetics. The biodegradability study showed that after 90 days of exposure, the hydrogels degraded to about 43% of their own mass. Therefore, the produced hydrogel could be an alternative adsorbent to remove pollutants and also for other potential applications.

Novel Stimuli-Responsive Pectin-PVP-Functionalized Clay Based Smart Hydrogels for Drug Delivery and Controlled Release Application

Stimuli-responsive drug delivery systems are urgently required for injectable site-specific delivery and release of drugs in a controlled manner. For this purpose, we developed novel pH-sensitive, biodegradable, and antimicrobial hydrogels from bio-macromolecule pectin, polyvinylpyrrolidone (PVP), 3-aminopropyl (diethoxy)methyl silane (3-APDEMS), and sepiolite clay via blending and solution casting technique. The purified sepiolite (40 um) was functionalized with 3-APDEMS crosslinker (ex-situ modification) followed by hydrogels fabrication. FTIR and SEM confirmed crosslinked structural integrity and rod-like morphology of hydrogels respectively. The swelling properties of hydrogels could be controlled by varying the concentration of modified clay in pectin/PVP blends. Moreover, the decrease in pH increased the swelling of hydrogels indicating the pH-responsiveness of hydrogels. All hydrogels were degraded after 21 days in phosphate buffer saline pH 7.4 (human blood pH). In-vitro cytotoxicity against 3T3 mouse fibroblast cell line analysis confirmed cytocompatibility of all hydrogels. Ceftriaxone sodium (CTX-S) was selected as a model drug. The release profile of the hydrogel showed 91.82% release in PBS for 2 h in a consistent and controlled manner. The chemical structure of the drug remained intact during and after release confirmed through UV-Visible spectroscopy. Overall, these hydrogels could be used as potential scaffolds for future biomedical applications.

Synthesis and Physicochemical Evaluation of Bees' Chitosan-Based Hydrogels Modified with Yellow Tea Extract.

The novelty of the research involves designing the measurement methodology aimed at determining the structure–property relationships in the chitosan-based hydrogels containing yellow tea extract. Performed investigations allowed us to determine the swelling properties of hydrogels in selected time intervals, evaluate the mutual interactions between the hydrogels and simulated physiological liquids via pH measurements and directly assess the impact of such interactions on the chemical structure of hydrogels using Fourier transform infrared (FT-IR) spectroscopy and their wettability by the measurements of the flatness of the drop on the surface of the tested samples via the static drop method. Next, the surface morphology of hydrogels was characterized by the Scanning Electron Miscorcopy (SEM) and their elasticity under the tension applied was also verified. It was proved that incubation in simulated physiological liquids resulted in a decrease in contact angles of hydrogels, even by 60%. This also caused their certain degradation which was reflected in lower intensities of bands on FT-IR spectra. Further, 23% v/v yellow tea extract in hydrogel matrices caused the decrease of their tensile strength. An increase in the amount of the crosslinker resulted in a decrease in the sorption capacity of hydrogels wherein their modification caused greater swelling ability. In general, the investigations performed provided much information on the tested materials which may be meaningful considering their application, e.g., as dressing materials.

Covalently Functionalized Carbon Nano-Onions Integrated Gelatin Methacryloyl Nanocomposite Hydrogel Containing γ-Cyclodextrin as Drug Carrier for High-Performance pH-Triggered Drug Release.

Herein, poly (n-(4-aminophenyl) methacrylamide)) carbon nano-onions (PAPMA-CNOs = f-CNOs) and γ-cyclodextrin/DOX-complex (CD) reinforced gelatin methacryloyl (GelMA)/f-CNOs/CD supramolecular hydrogel interfaces were fabricated using the photo-crosslinking technique. The physicochemical properties, morphology, biodegradation, and swelling properties of hydrogels were investigated. The composite hydrogels demonstrated enriched drug release under the acidic conditions (pH 4.5 = 99%, and pH 6.0 = 82%) over 18 days. Owing to the f-CNOs inclusion, GelMA/f-CNOs/CD supramolecular hydrogels presented augmented tensile strength (σult = 356.1 ± 3.4 MPa), toughness (K = 51.5 ± 0.24 Jg−1), and Young’s modulus (E = 41.8 ± 1.4 GPa). The strengthening of GelMA/f-CNOs/CD hydrogel systems indicates its good dispersion and the degree of polymer enveloping of f-CNOs within GelMA matrixes. Furthermore, the obtained hydrogels showed improved cell viability with human fibroblast cells. Nevertheless, the primed supramolecular hydrogels would pave the way for the controlled delivery systems for future drug delivery.

Supramolecular Hydrogels with Tunable Swelling by Host Complexation with Cyclobis(paraquat-p-phenylene)

Controlling the swelling properties of hydrogels is of primary importance for many applications ranging from actuators and valves to tissue engineering and drug delivery. Herein, we report the use of cyclobis(paraquat-p-phenylene) (CBPQT4+,4X–) as a versatile host to fine-tune the swelling behavior of 1,5-dialkyloxynaphthalene guest containing poly(N,N-dimethylacrylamide) hydrogels (NaphtGelz) through supramolecular host–guest complexation. While the equilibrium swelling of NaphtGelz in water decreases with increasing amount of hydrophobic naphthalene groups, the opposite behavior is observed with superabsorbing behavior (up to 180 times their initial dry mass) upon immersion in aqueous solutions containing the macrocyclic CBPQT4+,4X– due to formation of tetracationic host–guest complexes. In this case, the swelling amplitude could be conveniently programmed either by variation of the naphthalene content of the hydrogels or by controlling the stoichiometry of the host–guest binding events. Furthermore, by modifying the nature of the counterions (X = Cl–, Br–, and I–) of the tetracationic CBPQT4+ macrocyclic host, the swelling of the hydrogels could be tuned in line with Pearson’s absolute hardness scale of X–. The swelling behavior of these supramolecular hydrogels could be successfully described by a theoretical model, taking into account the hydrophobic association of the naphthalene groups and their screening by host–guest complexation. Finally, addition of sodium dodecyl sulfate as a surfactant to the supramolecularly swollen hydrogels led to a large decrease in hydrogel size due to dissociation of the host–guest complexes and the formation of CBPQT4+,4DS– within the hydrogel.

Effect of spent coffee grounds and rice husk amount towards the swelling properties of hydrogel using graft polymerization

Hydrogels are widely known for their ability to absorb water without being dissolved. This characteristic, which is known as swelling has been studied by many researchers in various sectors such as medicine, pharmacy, agriculture, health science and many more. This paper presents a study on the swelling properties of hydrogel that was grafted with spent coffee grounds and rice husk ash. The hydrogel was prepared with acrylic acid as the monomer and acrylamide as the co-monomer. The hydrogel was grafted with spent coffee grounds and rice husk ash separately, with varied weight percent (wt%). The hydrogel was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The 0.1 (wt%) rice husk ash grafted hydrogel has the best swelling properties as shown by the highest water absorption, with the most porous structure and the highest crystalline temperature (122.0 °C). The FTIR wavenumber showed that the hydrogel is grafted properly as new wavenumbers are formed, whereas the TGA analysis shown that it had the highest decomposition temperature (658.6 °C).

Gelatin/dextran‐based hydrogel cross‐linked by Diels–Alder click chemistry: the swelling and potassium diclofenac releasing

AbstractIn the present work, gelatin and dextran were derivatized in order to obtain a chemically cross‐linked hydrogel by Diels–Alder click chemistry reaction. The main interest in cross‐linking by the Diels–Alder reaction is the absence of by‐products and mild synthetic conditions, being a great advantage for biomedical applications. Thus, maleic anhydride (MA) and 2‐furoic acid (FA) were successfully grafted onto gelatin and dextran, respectively, making available the diene and dienophile groups for further cross‐linking. The derivatization was evaluated by nuclear magnetic resonance (NMR) spectroscopy, size‐exclusion chromatography (SEC) and differential scanning calorimetry (DSC). The Diels–Alder cross‐linking was confirmed by UV/Vis spectroscopy, and hydrogel behaviour was evaluated by rheological measurements. The hydrogel swelling properties and the cumulative release profile of diclofenac potassium (DFK) were studied in different dissolution media. The increase in swelling capacity was followed by faster DFK releasing from the platform, being the gelatin/dextran‐based Diels–Alder click hydrogel suitable for biomedical applications.

A pH-responsive carboxymethyl cellulose/chitosan hydrogel for adsorption and desorption of anionic and cationic dyes

A carboxymethyl cellulose/chitosan interpenetrating network hydrogel was prepared to adsorb and desorb anionic and cationic dyes applying different pH conditions. The three-dimensional network structure of the hydrogel was investigated using Scanning Electron Microscopy (SEM). Fourier Transform Infrared (FT–IR) was used to analyze the bonding mechanism of the hydrogel. The compression modulus of the hydrogel under neutral conditions exhibited an increase in parallel with the increase of carboxymethyl cellulose content. Under alkaline conditions, the swelling properties of hydrogels in water were enhanced with the increase of the carboxymethyl cellulose content. On the other hand, under acidic conditions, the swelling performance of hydrogels in water was decreased with the increase of carboxymethyl cellulose content. The adsorption capacity and desorption ratio of carboxymethyl cellulose/chitosan hydrogel for Acid Orange II were higher than 100 mg/g and 90%, respectively, while for Methylene Blue were higher than 110 mg/g and 95% even after five adsorption/desorption cycles. This study suggests that the carboxymethyl cellulose/chitosan interpenetrating network hydrogel showed different swelling behaviors under different pH values, which could present great potential as carrier materials in the controllable release-based applications.

Synthesis and Performance of Hybrid Hydrogels Loaded with Methylene Blue and Its Use for Antimicrobial Photodynamic Inactivation

Development and characterization of hybrid hydrogels loaded with methylene blue, which are designed to apply for photodynamic therapy, are presented. Hybrid hydrogels were synthesized by grafting polyacrylamide onto dextran/dextran sulfate sodium salt using N, N′-methylene-bis-acrylamide as a cross-linker. The differences in microstructure of synthesized hydrogels were proved by scanning electron microscopy. FTIR spectra testify that the chemical nature of hydrogel components affects the hydrogel hydrophilicity. The swelling properties of hydrogels in water and absorption/desorption hydrogels’ ability towards methylene blue were studied. It was shown that dye sorption was dependent on the hydrogel type. The hydrogel based on dextran and polyacrylamide revealed the highest ability to release absorbed dye. The bactericidal effect of this hydrogel loaded with methylene blue and activated by red light in suspension and solid medium of S. aureus was tested. The increase of bactericidal activity of hybrid hydrogel was dependent on radiation doses.

Effects of Biotin-Avidin Interactions on Hydrogel Swelling

Affinity interactions between the small molecule biotin and the protein avidin have been used extensively to functionalize biomaterials. More recently, researchers have leveraged the changes in biotin-avidin affinity that occur upon biotin conjugation to larger molecules to control the release of biotinylated drugs and proteins. However, the effects of biotin-avidin interactions on hydrogel properties have not been thoroughly investigated. The objective of this study was to evaluate the effect of increasing biotin and avidin concentrations on hydrogel swelling properties, as an indicator of crosslinking. Gelatin, selected as a model hydrogel material, was biotinylated at increasing fold molar excesses of biotin with a PEG linker using N-hydroxysuccinimide chemistry. Afterwards, biotinylated gelatin was formed into hydrogels and stabilized with glutaraldehyde. Swelling properties of the biotinylated hydrogels were investigated by conducting swelling studies in different avidin solutions. Increasing the degree of biotinylation caused significant decreases in swelling ratios of the hydrogels in a dose-dependent manner, suggesting increases in crosslinking of the hydrogels. However, increasing avidin concentrations in excess of biotin content did not significantly affect swelling ratios. Moving hydrogels to phosphate-buffered saline following avidin incorporation resulted in increased swelling ratios for hydrogels prepared with a lower concentration of biotin. However, hydrogels prepared with the highest concentration of biotin did not experience increased swelling ratios, implying that the stability of biotin-avidin-mediated crosslinking depends on the number of biotin molecules available for binding. Collectively, these results demonstrate that biotin-avidin interactions control hydrogel swelling properties, and that the magnitude and stability of the effects depend on the biotin concentration. These results have important implications for affinity-based controlled release of biotinylated drugs or proteins from biotin-avidin-crosslinked hydrogels.

Synthesis and characterization of novel semi-IPN nanocomposite hydrogels based on guar gum, partially hydrolyzed poly(acrylamide), and pristine montmorillonite

A range of new semi-interpenetrating polymer network (semi-IPN) nanocomposite hydrogels based on guar gum (GG)/partially hydrolyzed poly(acrylamide) (HPAm)/sodium montmorillonite (NaMMT) were synthesized in an aqueous solution by an in situ simultaneous cross-linking reaction between partially hydrolyzed polyacrylamide chains and chromium acetate as an ionic cross-linker in the presence of GG. Interactions occurring in the resulting hydrogels and examining the structure and morphologies of the prepared hydrogels were studied by various techniques such as TGA, DMA, FTIR, XRD, and SEM. The effects of GG/PAm weight ratio, cross-linking agent, and MMT nanosheets ratios were investigated and reaction variables optimized in response to hydrogel swelling properties. The morphological investigation revealed that MMTs were well dispersed in the nanocomposite matrix. The rheological analysis showed that the storage modulus of the semi-IPN nanocomposite hydrogels slightly raised with MMT addition up to 0.5 wt%, but it increased when the clay content was further growing. The equilibrium water absorbency of the semi-IPN gels in tap water and synthetic oil reservoir water slightly decreased as the concentration of the GG and MMT increased. The incorporation of MMT up to 1 wt% provided an improvement in the swelling capacity and further addition of it decreased the water uptake because of the participation in the cross-linking reaction, which enhanced the cross-linking density. Owing to the introduction of MMT, the nanocomposite hydrogels displayed higher resistance against syneresis in synthetic oil reservoir water as compared with unfilled hydrogels that is a desirable characteristic. The results indicated the novel MMT-based semi-IPN nanocomposite hydrogels can be potentially suitable for the chemically improved oil recovery area.

Chondrogenesis of cocultures of mesenchymal stem cells and articular chondrocytes in poly(l-lysine)-loaded hydrogels

This work investigated the effect of poly(l-lysine) (PLL) molecular weight and concentration on chondrogenesis of cocultures of mesenchymal stem cells (MSCs) and articular chondrocytes (ACs) in PLL-loaded hydrogels. An injectable dual-network hydrogel composed of a poly(N-isopropylacrylamide)-based synthetic thermogelling macromer and a chondroitin sulfate-based biological network was leveraged as a model to deliver PLL and encapsulate the two cell populations. Incorporation of PLL into the hydrogel did not affect the hydrogel's swelling properties and degradation characteristics, nor the viability of encapsulated cells. Coculture groups demonstrated higher type II collagen expression compared to the MSC monoculture group. Expression of hypertrophic phenotype was also limited in the coculture groups. Histological analysis indicated that the ratio of MSCs to ACs was an accurate predictor of the degree of long-term chondrogenesis, while the presence of PLL was shown to have a more substantial short-term effect. Altogether, this study demonstrates that coculturing MSCs with ACs can greatly enhance the chondrogenicity of the overall cell population and offers a platform to further elucidate the short- and long-term effect of polycationic factors on the chondrogenesis of MSC and AC cocultures.